Preprints
https://doi.org/10.5194/egusphere-2022-1255
https://doi.org/10.5194/egusphere-2022-1255
 
18 Nov 2022
18 Nov 2022
Status: this preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).

Global evaluation of Doppler velocity errors of EarthCARE Cloud Profiling Radar using global storm-resolving simulation

Yuichiro Hagihara1, Yuichi Ohno1, Hiroaki Horie1, Woosub Roh2, Masaki Satoh2, and Takuji Kubota3 Yuichiro Hagihara et al.
  • 1Radio Research Institute, National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan
  • 2Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan
  • 3Earth Observation Research Center, Japan Aerospace Exploration Agency, Tsukuba, Ibaraki 305-8505, Japan

Abstract. The Cloud Profiling Radar (CPR) on the Earth Clouds, Aerosol, and Radiation Explorer (EarthCARE) satellite is the first satellite-borne Doppler radar (EC-CPR). In our previous study, we examined the effects of horizontal (along-track) integration and simple unfolding methods on the reduction of Doppler errors in the EC-CPR observations, and those effects were evaluated using two limited scenes in limited latitude and low pulse repetition frequency (PRF) settings. In this study, the amount of data used was significantly increased, and the area of the data used was extended globally. Not only low PRF but also high PRF settings were examined. We calculated the EC-CPR-observed Doppler velocity from pulse-pair covariances using the radar reflectivity factor and Doppler velocity obtained from a satellite data simulator and a global storm-resolving simulation. The global data were divided into five latitudinal zones, and mean Doppler errors for 5 dBZe after 10 km integration were calculated. In the case of low PRF setting, the error without unfolding correction for the tropics reached a maximum of 2.2 m s-1 and then decreased toward the poles (0.43 m s-1). The error with unfolding correction for the tropics became much smaller at 0.63 m s-1. In the case of high PRF setting, the error without unfolding correction for the tropics reached a maximum of 0.78 m s-1 and then decreased toward the poles (0.19 m s-1). The error with unfolding correction for the tropics was 0.29 m s-1, less than half the value without the correction. The results of the analyses of the simulated data indicated that the zonal mean frequency of precipitation echoes was highest in the tropics and decreased toward the poles. Considering a limitation of the unfolding correction for discrimination between large upward velocity and large precipitation falling velocity, the latitudinal variation of the Doppler error can be explained by the precipitation echo distribution.

Yuichiro Hagihara et al.

Status: open (until 10 Jan 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Yuichiro Hagihara et al.

Yuichiro Hagihara et al.

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Short summary
We evaluated effectiveness of horizontal integration and unfolding method for the reduction of Doppler velocity error in the Level 2 algorithm of CPR. We used radar reflectivity and Doppler data from a global storm-resolving simulation and a satellite simulator. The Doppler error was higher in the tropics than in the other latitudes because of frequent rain echo occurrence and limitation of its unfolding correction. If we use low-mode operation (high PRF), the Doppler errors become small enough.